Giant amplification of tunnel magnetoresistance in a molecular junction: Molecular spin-valve transistor

Abstract

Amplification of tunnel magnetoresistance by gate field in a molecular junction is the most important requirement for the development of a molecular spin valve transistor. Herein, we predict a giant amplification of tunnel magnetoresistance in a single molecular spin valve junction, which consists of Ru-bis-terpyridine molecule as a spacer between two ferromagnetic nickel contacts. Based on the first-principles quantum transport approach, we show that a modest change in the gate field that is experimentally accessible can lead to a substantial amplification (320%) of tunnel magnetoresistance. The origin of such large amplification is attributed to the spin dependent modification of orbitals at the molecule-lead interface and the resultant Stark effect induced shift in channel position with respect to the Fermi energy. V

Boron Nitride Nanotubes for Spintronics

“…Because of the distinctive nature of the spin up and spin down electrons, they experience different scattering potential during the transport leading to a spin polarized current in the circuit [ 213 ]. Usually, depending upon the relative orientation of magnetization in the magnetic contact layers the circuit resistance changes from minimum resistance for the parallel magnetization (P) to maximum resistance for the anti-parallel magnetization (AP) between the contacts resulting in a spin-valve effect [ 45 , 49 – 53 , 55 , 212 ]— The foundation behind modern high density data storage devices. For a semiconducting channel, the relative resistance between the P and AP configurations is known as tunnel magneto resistance (TMR) [ 49 ].…”

“…Usually, depending upon the relative orientation of magnetization in the magnetic contact layers the circuit resistance changes from minimum resistance for the parallel magnetization (P) to maximum resistance for the anti-parallel magnetization (AP) between the contacts resulting in a spin-valve effect [ 45 , 49 – 53 , 55 , 212 ]— The foundation behind modern high density data storage devices. For a semiconducting channel, the relative resistance between the P and AP configurations is known as tunnel magneto resistance (TMR) [ 49 ]. The TMR value in general is higher than the magneto resistance observed in a spin-valve device with a metallic spacer, which makes the TMR device much more appealing [ 49 ] than the MR device with a metallic spacer.…”

“…For a semiconducting channel, the relative resistance between the P and AP configurations is known as tunnel magneto resistance (TMR) [ 49 ]. The TMR value in general is higher than the magneto resistance observed in a spin-valve device with a metallic spacer, which makes the TMR device much more appealing [ 49 ] than the MR device with a metallic spacer. CNT- and graphene-based spin-valve devices have been reported both theoretically and experimentally [ 54 – 59 ].…”

“…The bias range from 0 to 2 V is considered. The TMR value, which is obtained as (I PC − I APC )/I APC × 100% [ 49 , 50 , 52 ], is found to be ∼24% at a bias of ∼0.2 V ( Figure 10c ), suggesting that it can be used as a two terminal spin switch. Next, the transverse electric field (ε g ) is applied in the device to mimic the gate field in a three terminal spin transistor [ 213 ].…”

Fabrication of tunnel junction-based molecular electronics and spintronics devices

“…Similar to MTJ based MRAM array, in TJMD orthogonal lines can pass under and over the bit, carrying current that produces the switching field. According to theoretical studies molecules connected between two ferromagnetic electrodes can yield very high magneto resistance ratio [69,110]. A TJMD approach can utilize various MTJ configurations as the testbed and improvise its magneto resistance properties by bridging promising molecular channels.…”